1. Field of the Invention
This invention relates in general to magnetic transducers for reading information signals from a magnetic medium and, in particular, to an improved magnetoresistive read transducer.
2. Description of the Prior Art
The prior art discloses a magnetic transducer referred to as a magnetoresistive (MR) sensor or head which has been shown to be capable of reading data from a magnetic surface at great linear densities. An MR sensor detects magnetic field signals through the resistance changes of a read element made from a magnetoresistive material as a function of the amount and direction of magnetic flux being sensed by the element.
Numerous prior art MR sensors have been developed, and these prior art MR sensors have been effective to meet prior art requirements. However, the drive toward increased recording density has led to the requirement for narrower recording tracks and increased linear recording density along the tracks. The small MR sensors which are necessary to meet these requirements cannot be made with the use of the prior art techniques.
Japanese published unexamined patent application No. 57-198528 describes a MR head in which the MR element is separated from a magnetic biasing layer by an insulating layer. However, the track width Tw, over which the head is responsive to magnetic excitation, is determined by the physical spacing between signal pickup conductors.
U.S. Pat. No. 4,504,880 to Church et al discloses an integrated magnetic recording head which includes an inductive write head and an MR read element. The MR read element is in electrical contact with the two spaced conductors, so the effective track width of the MR read element is defined by the spacing between these conductors.
U.S. Pat. No. 4,568,906 to DeWilde et al shows a magnetic field sensitive element suitable for measuring magnetic field gradients in which the active part of the magnetic field sensitive element is defined by connection conductors which are in electrical contact with the magnetic field sensitive element.
As the track width becomes smaller it becomes progressively more difficult to adequately define the track width by the distance between spaced conductor elements. No prior art is known in which the track width of a small MR sensor is defined by a patterned insulator layer in contact with the MR sensor and over whose edges the conductor leads are deposited so that the insulator layer defines the track width.